To　identify　the　role　of　gut　microbiota　in　human　health　risk　assessment,　the　bioaccessibility　of　heavy　metals　in　14　soil　samples　were　determined　in　simulated　gastrointestinal　fluids.　Compared　to　the　small　intestinal　phase,　the　bioaccessibility　values　of　the　colon　phase　varied,　either　increased　by　3.5-fold　for　As,　by　2.2-fold　for　Cr,　and　by　1.6-fold　for　Ni,　or　reduced　by　4.4-fold　for　Cu,　respectively.　The　colon　incubation　with　adult　gut　microbiota　yielded　higher　bioaccessibility　value　of　As　(1.3　times)　and　Fe　(3.4　times)　than　that　of　the　child　in　most　soil　samples.　Colon　bioaccessibility　was　about　60%　greater　of　Cd　for　the　adult　and　30%　higher　of　Cr　for　the　child.　Congruent　data　on　the　bioaccessibility　of　Cu　and　Ni　was　observed.　In　addition,　correlation　analysis　indicated　that　in　vitro　bioaccessibility　was　primarily　related　to　total　concentrations　of　heavy　metals　in　soils,　followed　by　soil　pH　and　active　Fe/Mn　oxide.　Significantly,　risk　assessment　calculated　based　on　colon　bioaccessibility　indicated　that　the　target　hazard　quotient　(THQ　＞　1)　of　As　was　presented　in　3　soil　samples　for　the　adult　(1.05–3.35)　and　in　9　soil　samples　for　the　child　(1.06–26.93).　The　hazard　index　(HI)　of　the　child　was　4.00　on　average,　greater　than　that　of　the　adult　(0.62),　primarily　due　to　the　contribution　of　As　and　Cd.　It　suggested　non-carcinogenic　risks　are　likely　to　occur　in　children　through　typical　hand-to-mouth　behavior.　The　adjustment　of　colon　bioaccessibility　will　result　in　more　accurate　risk　assessment　of　human　exposure　to　heavy　metals　from　oral　ingestion　of　contaminated　soils.　©　2021　Elsevier　Ltd